Aeroelastic stability of a symmetric multi-body section model

Meccanica ◽  
2014 ◽  
Vol 50 (3) ◽  
pp. 731-749 ◽  
Author(s):  
Marco Lepidi ◽  
Giuseppe Piccardo
Keyword(s):  
Aeroelastic Stability ◽  
Section Model ◽  
Multi Body ◽  
Body Section

Simulation of Accessory Drive Belt Concerning to Slippage and Transversal Vibration

2006 ◽  
Author(s):  
Hiroshi Takagishi ◽  
Hiroshi Yoneguchi ◽  
Daichi Sakamoto ◽  
Atsushi Nagakubo
Keyword(s):  
Simulation Method ◽  
Dynamics Simulation ◽  
Design Stage ◽  
Friction Contact ◽  
Transversal Vibration ◽  
Body Dynamics ◽  
The Coefficient Of Friction ◽  
Drive Belt ◽  
Section Model ◽  
Multi Body

A simulation method was proposed to predict the slippage and transversal vibration of the accessory drive belt. To reproduce these phenomena, the accessory drive belt was represented by a section-by-section model in which the belt was replaced by a finite number of masses and springs using multi-body dynamics simulation. In this model, the belt was able to vibrate in both the direction of advance and the direction perpendicular to it, and a friction contact element was defined between the pulley and the belt. The coefficient of friction was made variable with respect to the slippage speed to enable stick and slippage to be predicted. This method allows for accurate simulation of the amount of belt slippage and the amplitude of transversal vibration, thus enabling the optimum belt layout to be determined at the design stage.

scholarly journals Effects of Structural Coupling on Mistuned Cascade Flutter and Response

1984 ◽  
Vol 106 (1) ◽  
pp. 17-24 ◽  
Author(s):  
R. E. Kielb ◽  
K. R. V. Kaza
Keyword(s):  
Coupled System ◽  
Aeroelastic Stability ◽  
Resonant Frequencies ◽  
Structural Coupling ◽  
Aerodynamic Loads ◽  
Natural Modes ◽  
Section Model ◽  
Cascade Flutter ◽  
The Stability ◽  
Two Degree Of Freedom

The effects of structural coupling on mistuned cascade flutter and response are analytically investigated using an extended typical section model. Previous work using two degree of freedom per blade typical section models has included only aerodynamic coupling. The present work extends this model to include both structural and aerodynamic coupling between the blades. The model assumes that the structurally coupled system natural modes have been determined and can be represented in the form of N bending and N torsional uncoupled modes for each blade, where N is the number of blades and, hence, is only valid for blade dominated motion. The aerodynamic loads are calculated by using two-dimensional unsteady cascade theories in the subsonic and supersonic flow regimes. The results show that the addition of structural coupling can affect both the aeroelastic stability and frequency. The stability is significantly affected only when the system is mistuned. The resonant frequencies can be significantly changed by structural coupling in both tuned and mistuned systems, however, the peak response is significantly affected only in the latter.

Dynamic Modelling of an Elephant Trunk Like Flexible Bionic Manipulator

2019 ◽  
Author(s):  
Mrunal Kanti Mishra ◽  
Arun Kumar Samantaray ◽  
Goutam Chakraborty ◽  
Aditya Jain ◽  
Pushparaj Mani Pathak ◽  
...  
Keyword(s):  
Spatial Dynamics ◽  
Dynamic Modelling ◽  
Bending Moment ◽  
Flexible Manipulator ◽  
Lumped Mass ◽  
Elephant Trunk ◽  
End Effector ◽  
Body Dynamics ◽  
Section Model ◽  
Multi Body

Abstract In this paper, an attempt is made to model and study the planar and spatial dynamics of flexible elephant trunk-like manipulator by using multi-body dynamics software MSC-ADAMS. The flexible manipulator is modelled for bending with variable curvature. The entire manipulator length is divided into two sub-sections with associated lumped mass, damping and stiffness for the dynamic analysis. In this model, each section has three pressure actuated bellow tubes, which are modelled as simple spring-damper with the net mass distributed at the ends. Besides, a torsional spring-damper system is also incorporated in each section model to resist the bending about the transverse axes when the pressures in the bellow tubes are unequal. The manipulator is so designed that due to different actuation forces (corresponding to different bellows), the resultant action is finally a bending moment at the tip of each section. The effect of the gravitational force is also included. The change in behaviour of the end-effector position and orientation with respect to time is studied along with the elongation of bellow tubes. The nature of the velocity profile of the end-effector is also determined to study the behaviour of the manipulator.

Stress fields in granular material and implications for performance of robot locomotion over granular media

2015 ◽  
Vol 8 (1) ◽  
pp. 2005-2009
Author(s):  
Diandong Ren ◽  
Lance M. Leslie ◽  
Congbin Fu
Keyword(s):  
Mechanical Properties ◽  
Granular Material ◽  
Granular Media ◽  
Rotation Frequency ◽  
Legged Locomotion ◽  
Working Environment ◽  
Navier Stokes ◽  
Maximum Speed ◽  
Sigmoid Curve ◽  
Multi Body

 Legged locomotion of robots has advantages in reducing payload in contexts such as travel over deserts or in planet surfaces. A recent study (Li et al. 2013) partially addresses this issue by examining legged locomotion over granular media (GM). However, they miss one extremely significant fact. When the robot’s wheels (legs) run over GM, the granules are set into motion. Hence, unlike the study of Li et al. (2013), the viscosity of the GM must be included to simulate the kinematic energy loss in striking and passing through the GM. Here the locomotion in their experiments is re-examined using an advanced Navier-Stokes framework with a parameterized granular viscosity. It is found that the performance efficiency of a robot, measured by the maximum speed attainable, follows a six-parameter sigmoid curve when plotted against rotating frequency. A correct scaling for the turning point of the sigmoid curve involves the footprint size, rotation frequency and weight of the robot. Our proposed granular response to a load, or the ‘influencing domain’ concept points out that there is no hydrostatic balance within granular material. The balance is a synergic action of multi-body solids. A solid (of whatever density) may stay in equilibrium at an arbitrary depth inside the GM. It is shown that there exists only a minimum set-in depth and there is no maximum or optimal depth. The set-in depth of a moving robot is a combination of its weight, footprint, thrusting/stroking frequency, surface property of the legs against GM with which it has direct contact, and internal mechanical properties of the GM. If the vehicle’s working environment is known, the wheel-granular interaction and the granular mechanical properties can be grouped together. The unitless combination of the other three can form invariants to scale the performance of various designs of wheels/legs. Wider wheel/leg widths increase the maximum achievable speed if all other parameters are unchanged.

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